1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// <optional>
// template <class U> T optional<T>::value_or(U&& v) &&;
#include <experimental/optional>
#include <type_traits>
#include <cassert>
#if _LIBCPP_STD_VER > 11
using std::experimental::optional;
using std::experimental::in_place_t;
using std::experimental::in_place;
struct Y
{
int i_;
Y(int i) : i_(i) {}
};
struct X
{
int i_;
X(int i) : i_(i) {}
X(X&& x) : i_(x.i_) {x.i_ = 0;}
X(const Y& y) : i_(y.i_) {}
X(Y&& y) : i_(y.i_+1) {}
friend constexpr bool operator==(const X& x, const X& y)
{return x.i_ == y.i_;}
};
#endif // _LIBCPP_STD_VER > 11
int main()
{
#if _LIBCPP_STD_VER > 11
{
optional<X> opt(in_place, 2);
Y y(3);
assert(std::move(opt).value_or(y) == 2);
assert(*opt == 0);
}
{
optional<X> opt(in_place, 2);
assert(std::move(opt).value_or(Y(3)) == 2);
assert(*opt == 0);
}
{
optional<X> opt;
Y y(3);
assert(std::move(opt).value_or(y) == 3);
assert(!opt);
}
{
optional<X> opt;
assert(std::move(opt).value_or(Y(3)) == 4);
assert(!opt);
}
#endif // _LIBCPP_STD_VER > 11
}
|
